Curable silicone compositions having enhanced cure-through-volume

ABSTRACT

A photocurable silicone composition which includes an additive which provides cure-through-volume of the overall composition. The additive is desirably a curable amino silyl-terminated polyorganosiloxane.

This application is a 371 of PCT/US01/14235 dated May 2, 2001

FIELD OF THE INVENTION

The present invention relates to curable silicone compositions havingenhanced cure-through-volume. More particularly, the present inventionrelates to curable silicone compositions incorporating as a propertyenhancing additive a curable amino functionalized silane or curableamino silyl-terminated silicone. Desirably the additive is analkoxy/amino silyl-terminated polymer composition which is the reactionproduct of a silanol-terminated polyorganosiloxane and at least twoend-capping silane components having different end-capping groups.

BACKGROUND OF RELATED TECHNOLOGY

Cure-through-volume (CTV) is an important property of photocurablesilicone compositions. Conventional curable silicone compositions havebeen limited in their ability to cure through wide bond gaps or inpotting applications requiring large depths. For example, CTV's of about2 cm to about 5 cm are typical of conventional curable silicones.Additionally, the use of filler materials and pigments further impedesthe ability of light curing sources to effectively penetrate thesilicone compositions.

To enhance CTV's, conventional methods have focused on either reductionor elimination of filler and pigment additives, or on the use ofpolymers which are capable of curing through more than one curingmechanism. For example, one approach has been to use silicone polymerswhich are capable of both photo and moisture cure. While compositionscontaining such polymers have their own advantages, it would bedesirable to have the ability to improve CTV without having to rely onsecondary curing mechanisms and the specialized polymers which aregenerally used therefor. Decreasing or eliminating filler materials hasnot been a viable alternative because the overall physical properties ofthe cured polymers are compromised, often to the point of beingcommercially unacceptable. Thus, there is a need for photocurablesilicone compositions which overcome the CTV limitations of conventionaltechnology and which are capable of curing through greater depthswithout jeopardizing the structural integrity of the cured silicone andwithout the need for polymers which rely on secondary curing mechanismsto increase CTV. Moreover, it would be advantageous to have aphotocurable silicone composition which is less sensitive to the levelof fillers or to the opacity of the composition as a whole.

SUMMARY OF THE INVENTION

The present invention relates to photocurable silicone compositionshaving enhanced physical properties, and particularly increased CTV, dueto the incorporation of a curable silicone-based additive. The curablesilicone-based additive may be incorporated in amounts sufficient toprovide enhanced CTV, elongation or other desirable properties. Forexample, incorporation of the additive in amounts of up to about 25% byweight of the total silicone composition, desirably in amounts of about0.1% to about 15% by weight, and more desirably in amounts of about 1%to about 2%, provides greater depth of cure and wider bond-gap curingthan similar compositions, including dual-curing silicone compositions,which do not incorporate the silicone-based additive.

In one aspect of the invention, there is included a photocurablesilicone composition which contains a.) at least one photocurablesilicone polymer; b.) a photoinitiator; and c.) at least one curableamino functionalized silicone or silane additive. Desirably the curableamino functionalized silicone additive includes a curable alkoxy/aminosilyl-terminated polymer or polymer blend which is formed from thereaction of a silanol-terminated polyorganosiloxane with one or moreend-capping silane components and desirably with at least twoend-capping silane components having different end-capping groups.

In another aspect of the invention there is included a method ofpreparing a photocurable composition having enhanced cure-through-volumecomprising the steps of (i) providing a photocurable silicone polymerand a photoinitiator; and (ii) incorporating therein a curablealkoxy/amino silyl-terminated polymer additive comprising the reactionproduct of at least one silanol terminated polyorganosiloxane and one ormore end-capping silane components and desirably with at least twoend-capping silane components having different reactive end-cappinggroups.

Another aspect of the invention includes a method of providing enhancedcure-through-volume (CTV) in a curable composition by applying theaforementioned silicone composition to a substrate and exposing it tosufficient light radiation to effectuate cure.

DETAILED DESCRIPTION OF THE INVENTION

Photocurable Silicone Component

The photocurable silicone component may be any photocurable siliconepolymer. Among the useful photocurable silicone polymers are thosedescribed in U.S. Pat. Nos. 4,675,346, 4,528,081, 5,300,608 and4,699,802, all of which are incorporated herein by reference.

More particularly, the reactive silicone polymers include those whichconform to the general structure:

wherein R¹ is H or alkyl C₁₋₁₀, desirably methyl; R² is a divalenthydrocarbon or hydrocarbonoxy group such as alkylene, alkyleneoxy,alkenylene or arylene; the R³ and R⁴ may be the same or different andare C₁₋₁₀ monovalent hydrocarbon radicals which are desirably alkyl,substituted alkyl, aryl, substituted aryl, alkoxy, aryloxy,(meth)acrylic, oxime, acetoxy, N,N-dialkylamino, N,N-dialkylamino,N-alkylamido or,

R is H or hydrocarbyl; R⁵ is C₁₋₁₀ monovalent hydrocarbon radical and nis an integer between about 1 and 1200. R² is desirably alkylene oralkenylene C₁₋₃, such as propylene and propenylene. Examples of usefulR³ and R⁴ groups are alkyls such as methyl and ethyl; halo alkyls, suchas trifluoropropyl; phenyl and benzyl. In the case where moisture curingis desired R³ and R⁴ will desirably be hydrolyzable groups and mostdesirably methoxy groups.

These reactive silicone polymers are desirably made from a materialhaving at least one end terminating in a silanol group. The process ofpreparing the photocurable silicone polymers includes reacting theaforementioned material having at least one end terminating in a silanolgroup with a silane containing at least one photocurable group, anddesirably more than one photocurable group.

The silanes useful for preparing the photocurable silicone polymers mayhave the general formula:

(R⁶)Si(OR⁷)₃  II

wherein R⁶ and R⁷ can be identical or different monovalent hydrocarbonradicals having C₁₋₁₀; R⁶ may also be a monovalent heterohydrocarbonradical having 1 to 10 carbon atoms wherein the hetero atoms areselected from the group consisting of halo atoms, O, N and S.

Desirably, R⁶ and R⁷ are selected from the group consisting of methyl,ethyl, isopropyl, vinyl, phenyl, methacryloxypropyl andnorbornenyltrimethoxy; and R⁷ is desirably selected from the groupconsisting of methyl, ethyl, isopropyl and CH₂CH₂OCH₃.

For example, one desirable silane is represented by the formula:

wherein R¹, R², R³ and R⁴ are as defined above.

Other polyalkoxysilanes useful in the present invention include:

Si(OCH₃)₄, Si(OCH₂CH₃)₄, Si(OCH₂CH₂CH₃)₄, (CH₃O)₃SiCH₃, (CH₅O)₃SiCH₃,

(CH₃O)₃SiCH═CH₂, (C₂H₅O)₃SiCH═CH₂,

(CH₃O)₃SiCH₂—CH═CH₂, (CH₃O)₃Si[CH₂—(CH₃)C═CH₂],

(C₂H₅O)₃Si(OCH₃), Si(OCH₂—CH₂—OCH₃)₄, CH₃Si(OCH₂—CH₂—OCH₃)₃,

CH₂═CHSi(OCH₂CH₂OCH₃)₃, C₆H₅Si(OCH₃)₃, C₆H₅Si(OCH₂—CH₂—OCH₃)₃,

(CH₃O)₃Si[(CH₂)₃O—CH₂—CH—CH₂], (CH₃O)₃Si[(CH₂)₃—Cl],

(CH₃O)₃Si[(CH₂)₃OOC(CH₃)C═CH₂], (C₂H₅O)₃Si(CH₂)₂CH₂—Cl,(CH₃O)₃Si(CH₂)₃NH₂,

(C₂H₅O)₃Si(CH₂)₃NH₂, (CH₃O)₃Si(CH₂)₃NH(CH₂)₂NH₂,(C₂H₅O)₃Si(CH₂)₃NH(CH₂)₂NH₂,

(CH₃O)₃—Si(CH₂)₃SH, (CH₃O)₃Si[(CH₂)₃OOCH₂═CH], and

Primary, secondary and tertiary amino silanes are also contemplated. Forexample, n-methylaminopropyltrimethoxysilane,n-ethylaminopropyltrimethoxysilane, n-butylaminopropyltrimethoxlsilane,n,n-diethylaminopropyl-trimethoxysilane,n,n-dimethylaminopropyltrimethoxysilane are all found to be useful.

The aforementioned silane components are reacted with one or moresilanol-terminated polymer components, which can be virtually any usefulsilanol-terminated material. Useful polymer components include fromabout 50 cps silanol-terminated polydimethylsiloxane, to about 150,000cps silanol-terminated polydimethylsiloxane and combinations thereof.The silanol-terminated polyorganosiloxane has the general formula:

HOSi—A—SiOH  II

wherein A represents a polymer or copolymer backbone, which can be anynumber of combinations of polyurethane, silicone, polyamide, polyetherand the like.

An example of one such silanol-terminated polymer backbone ispolydimethylsiloxane having the formula:

The number of repeating units will determine the molecular weight andhence the viscosity of this starting material. Thus, n can be, forexample, an integer which, for example, can be from about 1 to about1,200, desirably from about 10 to about 1,000. The viscosity of thesematerials is not critical and can easily be chosen to fit a particularproduct application, particularly because the terminated end product ofthis reaction will have substantially the same viscosity as thesilanol-terminated reactant. Viscosities of these silanol-terminatedpolymer backbone can range from about 1 cps to about 150,000 cps(Brookfield, 25° C.). Desirably, the silanol-terminated polymer backboneused in the present invention is from about 50 to about 150,000 cps.

The reaction to make the photocurable silicone polymers is efficientlyperformed using a catalytically effective amount of a catalyst, anddesirably of an organo-lithium reagent, as described in theaforementioned U.S. Pat. No. 5,300,608. The organolithium reagent can berepresented by the formula:

LiR¹⁴

wherein the organo group R¹⁴ may be C₁₋₁₈ alkyl, aryl, alkaryl,arylalkyl, alkenyl, alkynl, an amine-containing compound, or anorganosilicone-containing compound.

More particularly, if the organolithium reagent is an alkyl-lithium, itmay be selected from methyl-lithium, n-butyl lithium, sec-butyl lithium,t-butyl lithium, n-hexyl lithium, 2-ethylhexyl lithium, and n-octyllithium, among others.

Phenyl lithium, vinyl lithium, lithium phenylacetylide, lithium(trimethylsilyl) acetylide, lithium dimethylamide, lithium diethylamide,lithium diisopropylamide and lithium dicyclohexylamide are also usefulcatalyst reagents for forming the photocurable silicone polymer.

The organo group R¹⁴ may also be O(SiR¹¹R¹²O)_(t) SiR¹¹R¹²R¹³, whereinR¹¹ and R¹² are monovalent hydrocarbon radicals C₁₋₁₀; R¹³ is C₁₋₁₈alkyl or aryl; and t is an integer.

The catalyst used to prepare the photocurable silicone polymer is usedin catalytically effective amounts, desirably from about 1 to about 1000ppm based on the atomic weight of lithium.

The reaction process for making the photocurable silicone polymerincludes the addition of the silanol terminated organosiloxane,end-capping silane and organo-lithium solution into a reactor vessel.The mixture is then heated with stirring and in the absence of moisture,for example under nitrogen conditions, for about ½ to about 5 hours attemperatures of from ambient to about 110 degree. C., desirably from 25°C. to about 60° C., or until end-capping has been completed. The mixtureis then quenched with bubbled or liquid carbon dioxide or dry ice andfurther cooled. The formation of lithium carbonate can be easilyremoved, if desired, through filtration. Neutralization of the catalystis optionally carried out, preferably with carbon dioxide in the form ofdry ice. Acids may also be used for neutralization, as well as compoundssuch as silyl phosphate, silyl acetate and the like. Condensationmoisture aids in the neutralization process. Volatile materials, if any,are vacuum stripped. Equimolar amounts of the silanol-terminatedorganopolysiloxane (based on the moles of SiOH functionality) and theend-capping silane can be used in the reaction, but excess end-cappingsilane is preferred. In the preparation of a one-part dual curingcomposition, it is preferred to add only a slight excess of end-cappingsilane to control the potential viscosity increase. Thus, for example,in such cases 1.0 to 1.5 moles of alkoxysilane is preferred for everymole of silanol.

The reactive silicone compositions of the present invention may also becured using curing mechanisms or conditions other than photocuringconditions. For example, moisture curing, actinic radiation such as uvor visible light, heat, anaerobic cure or combination of thesemechanisms may be employed.

The resultant fluid can then be mixed with other conventional additivessuch as fillers, initiators, promoters, pigments, moisture scavengersand the like to form a one-part curable composition. Fillers such ashydrophobic fumed silica or quartz serve to impart desirable physicalproperties to the cured material. Moisture scavengers such asmethyltrimethoxysilane and vinyltrimethyloxysilane are useful.

Photoinitiator Component

The amount of photoinitator used in the composition will typically be inthe range of between about 0.1% and 5% of the composition. Depending onthe characteristics of the particular photoinitiator, however, amountsoutside of this range may be employed without departing from theinvention so long as they perform the function of rapidly andefficiently initiating polymerization of the photocurable groups. Inparticular, higher percentages may be required if silicone boundphotoinitiators are used with high equivalent weight per photoinitiatinggroup.

It should also be understood that while the photoinitiator is used as aseparate ingredient, the formulations used in the inventive method areintended to include formulations in which photoinitiating groups areincluded on the backbone of the same organopolysiloxane polymer whichincludes the photocuring groups discussed above. Preferred photocuringgroups which may be attached to the organopolysiloxane include acrylate,methacrylate and glycidoxy groups.

Curable Property-Enhancing Additive Component

The curable property-enhancing additive may be an amino functionalizedreactive silane, or more desirably is a curable amino silyl-terminatedpolymer or blend of such polymers. Most desirably the curableproperty-enhanced additive is one or more alkoxy/amino silyl-terminatedpolymer formed from the reaction of at least one silanol-terminatedpolymer with one or more end-capping silane components and desirablywith at least two silanes having different end-capping components. Thisreaction desirably occurs in the presence of a catalyst. The catalystreagent most desired may be any of the aforementioned organolithiumreagents used to make the photocurable silicone polymer componentdescribed herein.

The curable alkoxy/amino silyl-terminated polymer additive may be acombination of reactive silicone polymers, but includes desirably apredominant amount of an alkoxy/amino silyl-terminated end-cappedreactive polymer corresponding to the structure:

wherein A is a backbone portion selection from silanes, polyurethanes,polyesters and combinations thereof; n is an integer, for example, from1-1,200; A is desirably a polyorganosiloxane represented by therepeating structure:

wherein R¹ and R² may be identical or different monovalent hydrocarbonradicals C₁₋₁₀; desirably R¹ and R² are methyl groups; R³ and R⁵ aredifferent functional groups having up to 10 carbon atoms and areselected from (meth)acryl, amino (primary, secondary and tertiaryamines), vinyl, alkoxy, aryloxy, acetoxy, oxime and combinationsthereof; R³ or R⁵ may also be a monovalent heterohydrocarbon radicalhaving up to 10 carbon atoms (C₁₋₁₀), wherein the hetero atoms areselected from O, N and S; R⁴ is alkyl (C₁₋₁₀) and desirably methyl,ethyl or isopropyl; R⁴ may also be —CH₂CH₂OCH₃.

The curable amino/silyl-terminated polymer additive of the presentinvention provides for various hybrid end-capping combinations. Thecurable silyl-terminated polymer additive components are termed “hybrid”because their reactive terminal ends are different. For example, oneterminal silicon atom on the reaction product may have, directly orindirectly, alkoxy and amino functionality, while the other terminalsilicon atom has, directly or indirectly, alkoxy and vinylfunctionality. A particularly desirable reactive polymer formed by theprocess of the invention is a reactive silicone polymer having differentend-capped groups which include a combination of amino, vinyl and alkoxyterminal functional groups.

The curable amino or alkoxy/amino silyl-terminated polymer additive mayinclude a reaction product mixture which is a combination of a hybridend-capped reactive silicone combination with non-hybrid end-cappedreactive silicone. Desirably, the hybrid end-capped silicone is presentin a predominant amount as compared to non-hybrid silicone reactionproducts, and more desirably the hybrid is present in a predominantamount relative to the total reaction product combination.

Formation of the curable alkoxy/amino silyl-terminated polymer additiveis obtained by selecting predetermined amounts of each silane to obtainamino silyl-terminated, and desirably alkoxy/amino silyl-terminatedpolymers having different reactive end-capped groups. The silane orsilanes having slower reaction rates are desirably provided in excess ofthe silane having a higher reaction rate. The relative amounts of eachwill vary depending on the silanes chosen. Desirably, the ratio of onesilane to another is about 10:1 to about 1:10. In embodiments wherethree different silanes are added, a desirable ratio is about 1:2:1. Useof more than three silanes are also contemplated.

As previously mentioned, the curable alkoxy/amino silyl- or alkoxy/aminosilyl-terminated polymer additive may be a blend of polymers formed fromthe reaction of at least one silanol-terminated polymer with at leasttwo end-capping silane components having different reactive end-cappinggroups. This blend formed as the reaction product desirably has apredominate amount of a hybrid polymer as previously discussed. Theamounts of each silane necessary to obtain a predominant amount ofhybrid reaction product can be determined in advance. For example, priorto reaction, the hydroxy content of the silanol-terminated polymercomponent, e.g. silanol-terminated polyorganosiloxane, is determined bya suitable method. Based on the hydroxy content of thesilanol-terminated component, the total amount of silanes, as well asthe relative amounts of each, can be calculated to reach a predominantamount of the desired hybrid reaction product, or the desired ratio ofdifferent end-capping groups on the final reaction product. Desirably,the reaction products of the present invention comprise about 35% ormore, and more desirably about 60% or more silyl-terminated polymershaving different reactive end-capped groups. Other non-hybrid polymershaving reactive end-groups may also be present. Desirably, care is takenin determining the relative amounts of the silane components, to accountfor differences in their reaction rates and ensure that no one silane issubstantially unable to provide the desired end-capping. The totalamount of the silane components are desirably sufficient tosubstantially complete the end-capping reaction of thesilanol-terminated polymer or polymers. Desirably, about 0.5 moles toabout 4.5 moles of the silane components are added for every mole ofsilanol-terminated polymer backbone component.

Aminopropyldimethoxy/vinyldimethoxy terminated polydimethylsiloxanepolymers (hybrid DAM/VDM polymers) are examples of particularlydesirable curable alkoxy/amino silyl-terminated polymer additives of thepresent invention. This polymer additive is formed from reactingaminopropylalkoxysilane (DAM) and vinyl alkoxysilane (VDM) with asilanol-terminated polydimethylsiloxanes in a formulation ratio of17.67% by weight DAM to 82.33% by weight VDM, thereby producing a 1:1molar ratio of the amino to the vinyl functionality in the reactionproduct. The resultant reaction product is represented by a predominantamount of the reactive polymer having the following structure:

As examples of primary, secondary and tertiary amino silanes which canbe used as the property-enhancing additive aren-methylaminopropyltrimethoxysilane, n-ethylaminoprpyltrimethoxysilane,n-butylaminopropyltrimethoxsilane,n,n-diethylaminopropyltrimethoxysilane andn,n-dimethylaminopropyl-trimethoxysilane.

The invention may be further understood with reference to the followingnon-limiting examples. Percent weights are per the total compositionunless otherwise specified. Viscosities are measured using a Brookfieldviscometer with either a spindle #6 or #4 at 10 rpm, 25° C., unlessotherwise specified.

EXAMPLE I

A reactive silicone having the following composition was prepared inaccordance with the aforementioned process:

Composition A Components Weight % Methacryloxylpropyldimethoxy 77%polydimethylsiloxane Silicone oil poly(dimethylsiloxane) 3.3% Acrylicpolymer 5.5% Silicone Dioxide 3.3% Photoinitiator 3.3% ModifiedAcrylamide 2.2% *Silane adhesion promoter 3.3% *Substituted silanemoisture scavenger 1.1% *Non-amino containing silanes

To Composition A was added the curable alkoxy silyl-terminated polymeradditive in an amount of about 10% by weight of the total composition.This additive was a blend of alkoxy-silyl terminated reactive silicones,at least a predominate amount of which wasvinyldimethoxy/aminopropyldimethoxy terminated polydimethylsiloxane.

The entire reactive silicone composition was placed into an aluminumweighing pan and UV cured at 70 mW/cm² (365 nm) for 1 minute. The curedsample was removed from the pan and any uncured material was removedfrom the cured sample. The CTV was measured to be 6.1 mm. This is to becompared to the initial (Composition A without the curable polymeradditive) which had a CTV of 3.3 mm under the same cure conditions.

EXAMPLE II

Composition B, representing a conventional reactive siliconecomposition, was prepared having the following components:

Composition B Component Weight % Methacrylate terminatedPoly(dimethylsiloxane) 49.5% Vinyl terminated Poly(dimethylsiloxane) 31%Silicone oil poly(dimethylsiloxane) 3% Acrylate 5% Modified SiliconeDioxide 4.5% Photoinitiator 1% Modified Acrylamide 2% Silane adhesionpromoter 3% Substituted silane moisture scavenger 1%

Composition B was considered a control sample. Four additional sampleswere made using different quantities of the hybrid additivevinyldimethoxy/aminopropyl-dimethoxy terminated poly(dimethyl-siloxane)added to Composition B. Each sample was placed into individual aluminumweighing pans and UV cured at 70 mW/cm² (365 nm) for 1 minute. Eachcured sample was removed-from the pan and any uncured material wasremoved from the cured sample. The cured samples were then compared inCTV thickness to a cured sample of Composition B without an addition ofthe hybrid vinyldimethoxy/aminopropyl-dimethoxy terminatedpoly(dimethyl-siloxane) additive. The results from the five samples areshown in the Table I below.

TABLE I % Curable Amino Silyl-Terminated Hybrid Polymer Sample AdditiveCTV 1 (Control) None 5.5 mm 2 1.15% 7.5 mm 3 0.56% 6.1 mm 4 1.96% 8.5 mm5 3.05% 8.6 mm

As can be seen from Table I, the incorporation of the curablesilyl-terminated polymer additive significantly increased CTV ascompound to the control.

EXAMPLE III

Composition C, representing a conventional reactive silicone compositionwas prepared having the following components:

Composition C Component Weight % Methacrylate terminatedPoly(dimethylsiloxane) 66.5% Vinyl terminated Poly(dimethylsiloxane) 15%Silicone oil poly(dimethylsiloxane) 3% Acrylate 5% Modified SiliconeDioxide 3.5% Photoinitiator 1% Modified Acrylamide 2% Silane derivativeadhesion promoter 3% Substituted Silane moisture scavenger 1%

To Composition C was added aminopropyltrimethoxy silane at a 0.2% levelin place of the curable hybrid vinyldimethoxy/aminopropyldimethoxyterminated poly(dimethy)siloxane to determine the effect on the curethrough volume. This mixture was placed into an aluminum weighing panand UV cured at 180 mW/cm² (365 nm) for 30 seconds. The cured sample wasremoved from the pan and any uncured material was removed from the curedsample. The samples cure through volume was then measured to be 8.3 mmthickness.

EXAMPLE IV

Composition D, representing a conventional reactive silicone compositionwas prepared having the following components:

Composition D Component Weight % Methacrylate terminatedPoly(dimethylsiloxane) 70% Vinyl terminated Poly(dimethylsiloxane) 15%Acrylate 5% Modified Silicone Dioxide 3% Photoinitiator 1% ModifiedAcrylamide 2% Silane derivative adhesion promoter 3% Substituted Silanemoisture scavenger 1%

To Composition D was incorporated 1% of a the hybridvinyldimethoxy/aminopropyldimethoxy terminated poly(dimethyl)siloxaneadditive. This mixture was placed into a aluminum weighing pan and UVcured at 180 mW/cm² (365 nm) for 30 seconds. The cured sample wasremoved from the pan and any uncured material was removed from the curedsample. The samples cure through volume was then measured to be 10.3 mmthickness.

EXAMPLE V

Composition E

The CTV of a UV curing adhesive composition having as its reactivesilicone an acryloxymethyl-terminated poly(dimethyl-siloxane) was testedwith and without the inventive additive of the present invention todetermine effect on CTV. To Composition F was added 3.17% of the curablehybrid vinyldimethoxy/aminopropyldimethoxy terminatedpoly(dimethy)siloxane additive. Composition F without the additive wasused as a control. Both samples were placed into separate aluminumweighing pans and UV cured at 70 mW/cm² (365 nm) for 30 seconds. Thecured samples were removed from the pan and any uncured material wasremoved from the cured sample. The CTV of each sample was measured.Composition F with 3.17% of the hybrid curable polymer additiveincorporated therein had a CTV of 4.95 mm, as compared to Composition Fwithout the additive, which had a CTV of 4.70 mm.

What is claimed is:
 1. A photocurable silicone composition comprising:a. a photocurable silicone polymer; b. a photoinitiator; and c. acurable amino silyl-terminated polymer additive comprising the reactionproduct of at least one silanol-terminated polyorganosiloxane and at oneor more end-capping silane components.
 2. The composition of claim 1wherein said polymer additive is present in amounts sufficient toincrease CTV as compared to the same composition without said additive.3. The composition of claim 1 wherein said polymer additive comprises apredominant amount of a polymer corresponding to the structure:

wherein A represents a polymer or copolymer backbone selected from thegroup consisting of polyurethane, silicone, polyamide, polyether,polyester and combinations thereof and n is an integer 1 to 1,200; R³and R⁵ are different functional groups having up to 10 carbon atoms andare selected from (meth)acryl, amino, vinyl, alkoxy, aryloxy, acetoxy,oxime and combinations thereof, and either R³ or R⁵ may also be amonovalent heterohydrocarbon radical having up to 10 carbon atoms(C₁₋₁₀), wherein the hetero atoms are selected from O, N and S; R⁴ isalkyl) (C₁₋₁₀) or —CH₂CH₂OCH₃.
 4. The composition of claim 1 whereinsaid curable amino silyl-terminated polymer additive comprisesvinydimethyoxy/aminopropyldimethoxy terminated polydimethylsiloyane. 5.The composition of claim 1 wherein said polymer additive is present inamounts of about 0.2-15% by weight of the total silicone composition. 6.The composition of claim 1, wherein said photocurable silicone polymercorresponds to the structure:

wherein R₁ is H or alkyl C₁₋₁₀; R² is a divalent hydrocarbon orhydrocarbonoxy group; R³ and R⁴ may be the same or different and areC₁₋₁₀ monovalent hydrocarbon radicals; R⁵ is C₁₋₁₀ monovalenthydrocarbon radical and n is an integer from 1 to
 1200. 7. Thecomposition of claim 6, wherein said photocurable silicone polymercorresponds to the structure:

wherein R¹ is H or alkyl C₁₋₁₀; R² is a divalent hydrocarbon orhydrocarbonoxy group; R³ and R⁴ may be the same or different and areselected from the group consisting of alkyl, substituted alkyl, aryl,substituted aryl, alkoxy, aryloxy, (meth)acryl, oxime, acetoxy, N,N-dialkylamino, N,N-dialkylamines, N-alkylamido,

wherein R is H or hydrocarbyl and combinations thereof; R⁵ is C₁₋₁₀monovalent hydrocarbon radical and n is an integer from 1 to
 1200. 8.The composition of claim 1, wherein the photocurable siliconecomposition is also moisture curable.
 9. The composition of claim 1,wherein the photoinitiator is selected from the group consisting ofbenzoin, benzophenones, acetophenones and combinations thereof.
 10. Thecomposition of claim 8 further including a moisture curing catalyst. 11.A method of preparing a photocurable silicone composition havingenhanced cure-through-volume comprising the steps of: (i) providing aphotocurable silicone polymer and a photoiniatiator; and (ii)incorporating therein a curable amino silyl-terminated polymer additivecomprising the reaction product of at least one silanol-terminatedpolyorganosiloxane and one or more silane components.
 12. A method ofproviding enhanced cure-through-volume in a photocurable siliconecomposition comprising the steps of: (i) providing a photocurablesilicone composition comprising: a. A photocurable silicone polymer; b.a photoinitiator; and c. a curable amino silyl-terminated polymeradditive comprising the reaction product of at least onesilanol-terminated polyorganosiloxane and one or more end-capping silanecomponents; (ii) applying said photocurable silicone compositions to asubstrate; and exposing said silicone composition to sufficientradiation to photocure said silicone composition.
 13. A photocurablesilicone composition comprising: a. a photocurable silicone polymer; b.a photoinitiator; and c. a curable amino silyl-terminated polymeradditive comprising the reaction product of at least onesilanol-terminated polyorganosiloxane and one or more end-capping silanecomponents, provided that at least one of the end-capping silanecomponents is an amino containing component.
 14. A method of preparing aphotocurable silicone composition having enhanced cure-through-volumecomprising the steps of: (i) providing a photocurable silicone polymerand a photoiniatiator; and (ii) incorporating therein a curable aminosilyl-terminated polymer additive comprising the reaction product of atleast one silanol-terminated polyorganosiloxane and one or moreend-capping silane components, provided that at least one of theend-caping silane components is an amino containing component.
 15. Amethod of providing enhanced cure-through-volume in a photocurablesilicone composition comprising the steps of: (i) providing aphotocurable silicone composition comprising: a. a photocurable siliconepolymer; b. a photoinitiator; and c. a curable amino silyl-terminatedpolymer additive comprising the reaction product of at least onesilanol-terminated polyorganosiloxane and one or more end-capping silanecomponents, provided that at least one of the end-caping silanecomponents is an amino containing component; (ii) applying saidphotocurable silicone compositions to a substrate; and (iii) exposingsaid silicone composition to sufficient radiation to photocure saidsilicone composition.